Hypodermic syringe

ABSTRACT

A hypodermic syringe is described in which the needle (1) is protected by a guard. The guard includes a needle shroud (7) which is pivotable between open and closed positions and includes releasable locking means (9, 10, 12, 26, 31, 42, 43 and 44) to hold the guard respectively in open and closed positions. An operating arm (8) is attached to the needle shroud (7) to facilitate pivoting of the shroud form the open to the closed positions. Generally, shroud (7) is integrally moulded with arm (8) and needle boss (25) or with a sleeve (24) which can be fitted over boss (25).

This invention relates to hypodermic syringes and in particular providesa syringe which is safe in use.

Because of the growing prevalence of serious diseases which are spreadby contact with infected blood, e.g. infectious hepatitis and humanimmunodeficiency virus (HIV), it is important to dispose safely ofhypodermic syringes after use. Conventional practice is to supplyneedles separately packaged in a sealed tubular sheath. The needle canthen be screwed onto a standard syringe barrel and the sheath removed toexpose the needle for use.

After the injection has been given or the sample taken from the patient,the sheath is often replaced on the needle and the whole syringe placedin a disposal box for destruction. Unfortunately, the personadministering the injection may accidentally touch the end of theneedle, particularly when attempting to replace the sheath.

There is consequently a need to provide a safer method of protecting theneedles of syringes, particularly after use.

According to the present invention, there is provided a hypodermicsyringe having a needle guard which is pivotable between a firstposition in which it covers the tip of the needle and a second positionin which the needle tip is exposed and the guard lies in a positionwhich does not interfere with the use of the syringe.

Normally, the guard will include locking means for releasably holding itin said first and/or second positions. Particularly, when the guard ismanufactured in a plastic material, such locking means preferablyincludes projections or recesses which engage corresponding recesses orprojections formed in the base support for the needle or the needleboss.

Pivoting the needle guard between the second and first positions isconveniently achieved by application of finger pressure to a leverextension arm of the guard.

The needle guard is preferably moulded together with its operating armand the needle boss of the syringe as a single entity or with a fitting,such as a sleeve, which can be slid over a standard needle boss.

Further features and advantages of the syringe of the present inventionwill become apparent from the following description and accompanyingdrawings in which:

FIG. 1 is a perspective view of one embodiment of a hypodermic syringeneedle fitted with a guard in accordance with the invention.

FIG. 2 is a section through the guard and needle showing in solid linesthe guard in its first, closed position and in its second, open positionin broken lines,

FIG. 3 is a section similar to FIG. 2,

FIG. 3A is a section through the guard,

FIG. 4 is a section taken on the line A--A in FIG. 3,

FIG. 5 is a perspective view of the needle assembly with the guardremoved,

FIG. 5A is a perspective view (partly sectioned) of the guard,

FIGS. 6A to 6D are various views of a second embodiment of the inventionwhich includes an integrally moulded sleeve for attachment to a needleboss,

FIGS. 7A to 7C are views of a third embodiment of the invention in whichthe needle guard includes an integrally moulded needle boss,

FIGS. 8A to 8G are several views of a fourth embodiment of theinvention, FIGS. 8E to G illustrating its operation,

FIGS. 9A to 9N are views of a fifth embodiment of the invention in whichthe needle guard is moulded integrally with the needle boss.

Referring to the drawings and particularly, FIG. 1, the needle and guardassembly comprises a needle 1 of standard design and dimensions which issupported by a moulded plastics boss 2. Boss 2 is generally of standardform in so far as it is designed to be fitted at its lower portion 4 toa conventional hypodermic syringe barrel (not shown) and is sealed tothe lower end 3 of the hollow needle 1 in an upper portion 5 of reduceddiameter (see FIG. 4). Moulded to the outside of base portion 4 is apair of trunnions 6 on which a needle shroud 7 is pivotally mounted andconstitutes the effective part of the guard.

Shroud 7 (and also needle boss 2) are preferably injection moulded froma thermoplastics material. As best seen in FIG. 1, shroud 7 has agenerally trough-shaped form and in its closed position, shrouds theneedle on three sides and covers the tip.

An extension arm 8 is integrally moulded with the main body of theshroud 7 and facilitates pivoting of the guard from its open, operativeposition as shown in broken lines in FIG. 2, to its closed, protectiveposition, shown in solid lines in FIG. 2.

Locking of the shroud in the open and closed positions may be achievedby cooperating features moulded in the shroud 7 and the boss 2. Thesemay take the form of projections moulded on one of these componentswhich engage with a corresponding recess in the other component. Thus,the shroud 7 may be moulded with a projection 9 which is adapted to be asnap fit into a corresponding recess 10 formed in the boss when theshroud is pivoted into the closed position. Similarly, the shroud may bemoulded with a similar projection 11 which is adapted to form a snap fitwith a recess 12 when the shroud is pivoted into its open position.

It will be appreciated that other devices may be moulded to the shroudand/or needle boss to retain the guard in the closed and operativepositions. For example, the walls of the shroud may be tapered inthickness so that when pivoted in one position, the shroud is pressedmore tightly against the boss.

It may also be desirable to provide some means to prevent re-use of thesyringe. This may be achieved, for example, by moulding a resilientfinger or fingers to the inside faces of the shroud. The finger isnormally trapped between the boss and the inner wall of the shroud butwhen the shroud is closed and pivoted into an `over-centre` position,the finger is released and engages with a recess in the boss, thuspreventing removal of the guard and re-use of the needle.

As best seen in FIG. 5A, the guard is moulded with holes 13 to receivetrunnions 6 and a tapered lead slot 14 so that in manufacture themoulded shroud 7 can be pushed onto the trunnions 6. A thermoplasticsmaterial is chosen which has sufficient flexibility that the trunnionswill ride up the lead slot 14 and snap into holes 13.

After assembly of the guard onto the needle, the resulting assembly maybe packaged in a sterile pack, such as a shrink-wrap film, and providedwith a tear-strip to ease removal of the film prior to use.

FIG. 6A is a perspective view of an embodiment in which the needle guardis moulded integrally with a sleeve which is adapted to fit over aneedle boss. The needle shroud portion 7 has an operating arm 8 attachedto one side by a flexible strap 20. On the side remote from strap 20,shroud 7 is attached to a sleeve 21 by a plastic hinge 22. The end ofarm 8 remote from shroud 7 is also attached by a flexible hinge 23 tosecond sleeve 24. Sleeves 21 and 24 are internally shaped anddimensioned so that they fit over a standard needle boss and areanchored tightly thereon. As shown in FIG. 6D, the elements of the guardare flexibly interconnected and can be readily manufactured as a singlemoulding, e.g. by injection moulding.

FIGS. 6B and 6C show the manner in which the guard is operated. Theguard is desirably packaged together with the needle and its attachedboss in the manner shown in FIG. 6C. A syringe body can then be attachedto the needle boss in the usual way and any packaging film or outerpackaging removed from the needle guard/needle assembly. Needle shroud 7is then gripped and pivoted into the position shown in FIG. 6B. In thisposition, the syringe is filled with the medication to be administeredand the injection given or the sample taken from the patient. At thisstage, the tip of the needle is contaminated with blood and the needleshroud 7 is snapped back into the guarded position shown in FIG. 6C bydownward thumb pressure on the arm 8 without any risk of touching thetip. The guarded needle can then be discarded safely while the tipcontinues to be protected by the shroud 7. Strap 20 is provided with aslot and opening 26 into which the upper part of the boss 25 engageswhen the needle shroud is in its open position (FIG. 6B), so as to holdthe shroud steady in this position. Similarly, the lower part of theneedle shroud may be shaped so as to engage the needle boss in theclosed position. One or more corresponding protrusions and recesses 27and 28 may be formed on the sleeves 21 and 24 in order to inhibittwisting of the sleeves on the needle boss.

FIGS. 7A, B and C illustrate a modification of the embodiment of FIGS.6A, B , C and D in which the main difference is that a needle boss ismoulded integrally as part of the guard. The same reference numerals areused to indicate parts in this embodiment which are the same of similarto those in the FIG. 6A embodiment. FIG. 7A shows the needle guard inthe initial and final closed positions in full lines and in its openposition in broken lines. The method of operating the needle guard andusing the syringe is essentially identical to that described inconnection with FIG. 6A, B, C and D. Referring to FIG. 7A, this showsthe most convenient configuration for moulding the needle guard. As canbe seen, a needle boss 25 is connected by an integral flexible strap 29to arm portion 8. Needle boss 25 is similar to standard needle bossesexcept that it incorporates an anchor point 30 for attachment of theintegral strap 29. FIG 7C shows in plan view a part of the moulding FIG.7B. Aperture 26 is connected to slot 26a via a throat which resilientlyretains the needle shroud in its open position. The restricted width ofthe slot 26a compared with diameter 31 also means that there is aresistance to pivoting the needle guard into its open position. This hasthe effect of providing a resilient biasing against pivoting of theneedle guard out of its open or closed positions. In other words, it isnecessary to exert a positive pivoting force on the needle shroud tomove it from one of its two rest positions, i.e., fully closed and fullyopened.

FIGS. 8A, B, C, D, E and F show a further modification of the embodimentshown in FIG. 6A. Again, the same reference numerals are used toindicate corresponding parts. The major difference is that the operatingarm 8 is connected to a hinge 32 connected to a forked portion whichcloses off the base of the open side of shroud 7. In the open positionof the shroud shown in FIG. 8C, forked portion 33 lies on the shoulder34 of needle boss 25. Shroud 7 may be resiliently held in this positionby ears 35 engaging over sleeve 21. Downward thumb pressure on arm 8causes the shroud 7 to return to the closed position by forked portion33 riding over shoulder 34. This downward pressure on arm 8 causes thesleeve 21 to slide downwardly over boss 25 until the shroud snaps backinto the closed position. Because needle bosses are normally tapered,sleeve 21 must usually be broken as shown in FIG. 8A to 35. The sequenceof relative movement between the sleeve 21 and the boss 25 isillustrated in FIGS. 8D to 8G. This embodiment also includes at 36, (seeFIGS. 8A and 8B), a foam insert in the tip of shroud 7 which ispositioned to absorb any drops of blood which may be adhering to theneedle tip. If desired, this feature can be included in any of theembodiments.

FIG. 9A shows a further embodiment in which the needle shroud 7 ismoulded integrally with a needle boss. Although the moulding is a littlemore complex in this embodiment, the mechanics of the hinge movement arebetter than the arrangement shown in FIGS. 6A and 7A and for this reasonamong others it is currently preferred. In FIG. 9A, the needle shroud 7is shown in full lines in an intermediate position, between open andclosed positions, in which it is conveniently moulded together with aneedle boss and interconnecting hinge. As in all embodiments, the needleis sealingly fixed into the boss, e.g. with adhesive or by heatsoftening the tip of the boss just prior to packaging the needle/guardassembly. FIG. 9A additionally shows in ghosted lines the open andclosed positions of the needle shroud. Needle shroud 7 is connected toneedle boss 25 by integrally moulded hinge element 40. Because theneedle assembly is moulded in its intermediate position, pivotingmovement of the shroud in its open position tends to stretch the hingeelement and this stress assists the movement of the shroud into itsclosed position in a smooth action. Also the thumb pressure on the arm 8is translated into a pulling action, via hinge 40, on the upper end ofthe needle boss 25. Since the shroud 7 pivots about the heel 41 of theshroud, this action generates a moment equal to appropriately the heightof the needle boss which is effective in closing the shroud around theneedle.

FIG. 9B is a perspective view, partially in section and FIG. 9C is asimilar but full perspective view showing the connection of shroud 7 tothe needle boss solely by the integrally-moulded hinge or strap 40. Thearm 8 is shown as solid plastic, although it will be appreciated thatthis could be hollowed somewhat to save material.

In FIG. 9D, the same embodiment is shown in its closed position inlongitudinal section and giving a better view of the shape of the heelportion 41.

FIGS. 9E and F are longitudinal sections at two different depths throughthe needle guard assembly and FIG. 9G is a plan view from below. A pairof longitudinal ribs 42 moulded on the outside of the needle boss 25 areclearly apparent in FIGS. 9F to 9G as well as in FIG. 9C. Ribs 42contact a pair of abutment 43 in the closed position. Abutments 43 aremoulded on the inside of shroud 7 and move over ribs 42 when the shroudis pivoted into its open position and accordingly resilient restrain theshroud in the closed position. An additional pair of abutments 44 aremoulded on the inside of the shroud in such a position as to engage ribs42 when the shroud is in its open position and these resiliently holdthe shroud steady until the resistance is overcome by pressure on arm 8to cause the shroud to close. The pivoting movement of the shroud 7about the needle boss 25 and the engagement of the abutments 43 and 44with the ribs 42 in the open and closed positions is shown more clearlyin FIGS. 9H, 9J and 9K.

FIG. 9N is a further side elevation, partly in section, of theembodiment of Figure in its preferred moulding position and FIG. 9P is aplan view, seen from below, of FIG. 9N. Cross-sectional views takenrespectively along the lines 1, 2, 3 and 4 in FIG. 9N are illustrated inFIGS. 9N1, 9N2, 9N3 and 9N4. It will be appreciated from these viewsthat this embodiment can be mounted by using appropriate insert tools,introduced from above and below.

I claim:
 1. A hypodermic syringe having a needle guard which ispivotable between a first position in which it covers the tip of theneedle and a second position in which the needle tip is exposed and theguard lies in a position which does not interfere with the use of thesyringe by finger pressure applied to a lever extension portion of saidguard, said guard being moulded integrally with a boss for supportingthe needle or with a sleeve which is adapted to be fitted over a needleboss, the needle guard being connected to the needle boss or to saidsleeve by a flexible, integrally moulded strap and wherein the guard isconnected by a plastic hinge to a second sleeve which is adapted to befitted over the needle boss.
 2. A syringe according to claim 1 in whichthe guard includes means for releasably holding it in said first andsecond positions.
 3. A syringe according to claim 1 or claim 2 in whichthe guard comprises a generally through-shaped shroud which is adaptedto shroud the needle on three sides and to protect the tip in said firstposition and in which the shroud is pivotably mounted at the base of theneedle so that on pivoting the shroud from said second to said firstposition, the needle enters the open side of the trough-shaped shroud.4. A syringe according to claim 1 wherein said strap connects said leverextension portion of the guard to the needle boss or sleeve and whereinflexing of the strap allows the guard to pivot between said first andsecond positions.
 5. A needle assembly for a syringe which comprises aneedle boss having a needle projecting therefrom, a needle guardintegrally attached to the needle boss by a flexible strap, whichincludes a guard-operating arm portion, said guard including a shroudportion which, in a first position, is capable of protecting the needletip and in a second position, allows the needle to be used with asyringe, the flexible strap permitting movement of said guard from saidfirst to said second position and forms a loop with the needle boss sothat finger pressure on said arm portion causes return movement of saidguard.
 6. A needle assembly according to claim 5 which includesintegrally moulded engagement means on said guard and/or on said bossfor biasing the guard against pivoting out of its open or closedpositions.
 7. A hypodermic syringe having a needle boss and needleconnected to a barrel, a plastic moulded needle guard including anintegrally-moulded sleeve for retaining the needle guard on the boss,said guard including a shroud portion which, in a first position iscapable of protecting the needle tip and in a second position allows theneedle to be exposed and used, the shroud portion being connected to thesleeve portion by a strap portion permitting movement of the shroudportion from said first to said second position and wherein the shroudportion includes an integrally moulded operating lever linked to thesleeve by said strap, whereby finger pressure on said arm portion causesreturn movement of the shroud portion to said first position.